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IS 9841 (1981): Guide for treatment and disposal ofeffluents of fertilizer industry [CHD 32: EnvironmentalProtection and Waste Management]

Indian Standard

IS : 9841 - 1981 ( Reaffirmed 1995 )

GUIDE FOR TREATMENT AND DISPOSAL OF EFFLUENTS OF FERTILIZER INDUSTRY

( Secmd Reprint FEBRUARY 199X )

UDC 628.543 (026) ; 63 l-8

8 CopVrrghr 1981

BUREAU OF JNDIAN STANDARDS MANAK BHAVAN, 9 BAHADUR SHAH ZAPAR MARG

NEW BElx1 llooo2

G’ 9 November 1981

IS : 9841 - 1981

Indian Standard GUIDE FOR TREATMENT AND DISPOSAL OF

EFFLUENTS OF FERTILIZER INDUSTRY

Water Sectional Committee, CDC 26

Chr/irtmn Representing

DR T. R. BHASKARAN Geo Miller & Co Pvt Ltd, Calcutta

Members

SHRI S. BHiIOTHALINGAhl Kerala State Board for the Prevention & Control of Water Pollution, Trivandrum

SHRI J. D. JOYSINCH ( Alternate ) CHIEF WATEK ANALYST, KINCI Director of Public Health, Government of Tamil 1 SW WTE, MADRAS Nadu, Madras

SHKI L. M. CHOUDHRY Haryana State Board for the Prevention & Control of Water Pollution, Chandigarh

SHKI M. L. PRABHA~AR (Alternate ) SHRI M. V, DESAI Indian Chemical Manufacturers’ Association,

Calcutta SHRI MANGAL SINGH ( Alternafe )

SHRI H.P. DIJBEY National Test House, Calcutta SHRI B. K. DUTTA The Fertilizer ( Planning & Development ) India

Ltd, Sindri SHRI G. S. RAY ( Alternate 1

SHKI R. C. DWI~EDI Uttar Pradesh Water Polhtion Prevention and Control Board, Lucknow

’ SHRI R. N. SEN ( Alternate ) SHRI P. GANC‘IULY The Alkali & Chemical Corporation of India Ltd,

Calcutta SHRI P. K. CHAKRAVARTY ( Alternate )

SHRI K. L. GHOSH Regional Research Laboratory

DR P. K. GUPTA Bhubaneshyar

( CSIR 1,

Natige;fii Physlcal Laboratory ( CSIR ), New

SHRI JITENDRA RAI ( Alfernate ) DR M. I. GURBAXANI The Tata Iron & Steel Co Ltd, Jamshedpur SHRI S. HANUMANTH RAO Karnataka State Board for Prevention & Control

of Water Pollution, Bangalore SHRI C. H. GOVINDA RAO ( Alternate )

SHRI C. P. JAIN Central Electricity Authority, New Delhi SHRI J. JHA ( Alternate )

( Continued on page 2 )

@ Copyrlghr 1981 BUREAU OF INDIAN STANDARDS

This publication is protected under tho I&an Copyrlghf Acr ( XIV of 1957 ) and reproduction in wholo or in part by any mean8 except with written pormirrlon of the publbbor ahall bo doemod to be 81) infrigement of copyright under the raid Act.

IS : 9841- 1981

( Continued from puge 1 )

Members Represetrring

SHRI MALLINATH JAIN Delhi Water Supply & Sewage Disposal Under- taking, New Delhi

SHRI K. R. SAHU ( Allernute) JOINT DIKLCTOK (CHEM ), RDSO, Railway Board ( Ministry of Railways )

LUCKNOW ASSISTANT CHEMIST & METAL.

LURGIST, N. E. RLY, GORAKHPUR ( Alternate ) SHRI M. S. KRISHNAN Bhabha Atomic Research Centre, Bombay SHRI V. N. LAM~U lon Exchange ( India ) Ltd, Bombay

SHKI M. S. BIIXAKAK ( Alternate ) SHRI S. MAHAUEVAN Bharat Heavy Electricals Ltd, Hyderabad

SHRI G. KKISIINAYYA ( Altermte I ) DR A. PKABHAKAR ho ( Alrrmutc I1 )

SHRI V. K. MALIK All India Distillers’ Association, New Delhi SHRI K. SURIYANARAYANAN ( Alternute 1

SHKI K. MANIVANNAN Director of Industries, Government of Haryana, Chandigarh

PKOF R. S. MEHTA Guiarat Water Pollution Control Board, Gandhi- nagar

SHRI M. D. DAVE ( Alternate ) SHR~ S. K. MI.~.HA West Bengal Prevention & Control of Water

Pollution Board, Calcutta Municipal Corporation of Greater Bombay M. P. State Prevention Xr Control of Water

Pollution Board, Bhopal

MUNICIPAL ANALYST SHRI D. V. S. MUKTHY

SHRI P. K. BANERJEE ( Alternate ) SHRI R. NATARAJAN

SHRI B. M. RAHUL ( Alternate ) SHRI S. K. NEOC~I Institution of Public Health Engineers, India,

Calcutta DR M. BANERJEE ( Alternate )

DR V. PACHAIYAPPAN DR R. N. TIUVEDI ( Alternate )

SHRI R. PARAMASIVAM

The Fertiliser Association of India, New Delhi

National Environmental Engineering Research Institute ( CSIR ), Nagpur

SHRI M. V. NANOTI ( Alternate ) PROF S. C. PILLAI SHRI A. K. PODDAK

SHRI A. K. DAS ( Alternate )

SHRI H. S. PrRI

Indian Institute of Science, Bangalore Steel Authority of India Ltd, New Delhi

Punjab State Board for the Prevention and Control of Water Pollution, Patiala

SHRI QIMAT RAI ( Alternate ) SHRI B. B. RAO Ministry of Works & Housing

DR I. RADHAKRISHNAN ( Afternate 1 SHRI B. V. ROTKAR Central Board for the Prevention & Control o

Water Pollution. New Delhi

Bombay Chamber of Commerce & Industry, Born bay

DR K. R. RANGANATHAN ( Alternare ) SHRI K. RUDRAPPA Engineers India Ltd, New Delhi

SHRI S. N. CHAKRABARTI ( Alternate )

( Continued on page 41

2

IS : 9841 - 1981

Indiun Standard GUIDE FOR TREATMENT AND DISPOSAL OF

EFFLUENTS OF FERTILIZER INDUSTRY

0. FOREWORD

0.1 This Indian Standard was adopted by the Indian Standards Institution on S June 1981, after the draft finalized by the Water Sectional Committee had been approved by the Chemical Division Council.

0.2 A number of nitrogenous and phosphatic fertilizer factories ha\c been commissioned in Tndia in the last three decades and more are either under installation or planned for installation in the coming years. These fcrtiliser factories arc located throughout India, depending on the proximity of the raw material source, availability of water and power and distribution of finished product. The efllucnt disposal facility has also been considered recently in deciding the factory site.

0.3 The production of fertilizers requires a huge quantity of water for various uses. A substantial part of this water after use in the process finds its way out contaminated with various pollutants. These effluents finally flow to the nearby inland surface waters, coastal waters, or on land causing water pollution problems.

0.4 Considerable work has been done in India and abroad on proper treatment and disposal of these effluents and information and data on the subject are now available. These data and information have formed the basis for the preparation of this standard. While realizing that any effluent treatment process has the inherent scope for being further improved, the Committee responsible for the preparation of this standard has given careful consideration to the feasibility of the methods available in literature and has been of the view that effective measures can now be taken for abatement of pollution. It is hoped that the industry, public health authorities and other agencies concerned with water pollution control in different parts of the country will find this standard useful.

0.5 The object of this standard is to compile information on methods of treatment of effluents and to make definite recommendations for their treatment in India. The standard does not seek to provide detailed information on the working of a plant or on the designing and operation of the effluent treatment plant.

Further, the methods recommended for adoption have been selected taking into consideration the practicability of their adoption by the industry.

3

IS: 9841- 1981

When better and more economic methods of treatment become available, revision of this standard will be taken up. A list of relevant references is given in Appendix A.

0.6 It is recommended that plants located near the sea may preferably discharge their effluents into the marine coastal area rather than into inland surface water. The extent of pollution of marine coastal areas permitted by discharge of efYuents is laid down in IS : 7967-1976*.

0.7 The extent of pollution of inland surface waters permitted by discharge of effluents is laid down in IS : 2296-1974-t. The following Indian Standards lay down tolerance limits for industrial effluents :

IS : 2490 (Part I)-1974 Tolerance limits for industrial effluents discharged into inland surface waters : Part I General limits (first revision )

IS : 2490 (Part VIII)-1976 Tolerance limits for industrial effluents discharged into inland surface waters : Part VIII Phos- phatice fertilizer industry (first revision )

IS : 2490 ( Part IX)-1977 Tolerance limits for industrial effluents discharged into inland surface waters : Part IX Nitrogenous fertilizer industry (fjrst revision)

IS : 3306-1974 Tolerance limits for industrial effluents discharged into public sewers ( first revision )

IS : 3307-1977 Tolerance limits for industrial effluents discharged on land for irrigation purposes (first revision )

IS : 7968-1976 Tolerance limits for industrial effluents discharged into marine coastal areas.

0.8 Methods of sampling and test for industrial effluents are covered in various parts of IS : 24881.

1. SCOPE

1.1 This standard covers methods of treatment and disposal of effluents from nitrogenous and phosphatic fertilizer industry. It includes available data and information on the sources, characteristics, volumes, pollutional effects of the effluents, ways of waste prevention and methods of their treatment and disposal.

*Criteria for controlling pollution of marine coastal areas. TTolerance limits for inland surface waters subject to pollution (first revision ). $Methods of sampling and test for industrial effluents :

Part I - 1966 Part IV - 1974 Part II - 1968 Part V - 1976 Part III - 1968

4

1s : 9841 - 1981

2. DESCRIPTION OF PHOCE:SSES INVOLVEI)

2.0 General - Nitrogenous fertilizer industry is mainly concerned with the production of fertilizers like urea. ammonium sulphate, ammonium-nitrate, calcium ammonium nitrate ( CAN ). ammonium chloride, etc. Phosphatic fertilizer category manufactures mainly single superphosphatos, triple super- phosphates, nitrophosphates, ammonium phosphates. etc.

2.1 Nitrogenouo Fertilizer Industry

2.1. I .4~mzotziu Production - In the production of nitrogenous fertilizer anlmonia is the basic intcrmctliatc product. Ammonia is produced by reaction of hydrogen with nitrogen. This reaction is carried out in a co~i- vcrtcr in the presence of iron catalyst promoted with metal nxidcs at elcvatcd pressure, which favours ammonia formation. The raw material source ot‘ nitrogen is atmospheric air or pure nitrogen from an air liquefac- Zion plant. Hydrogen OII the other hand is obtatned from a variety of so LI rcec namely naphtha, fuel oil, coal, natural gas, coke-o\.en gas, hytlro& rich refinery gas. electrolytic hydrogen off-gas, etc. The production of ammonia from the above feed stock involve< three main steps : preparation of‘ raw synthesis gas, purification of the gas mixture and synthesis of ammonia.

2.1.1.1 The process adopted for synthesis gab preparation depends on the fccdstock used. Where a cheap source of electricity is available, electrolysis 01‘ water yields hydrogen off-gas with the production of heavy water. In India only one such unit is operating at present. In the partial oxidation process hydrocarbon feedstock and oxygen or oxygen enriched air arc prehcatcd and reacted at high temperature and pressure to form carbon monoxide and hydrogen. The raw gas is scrubbed with water for removal of the carbon formed during gasification and after desulphurization is sent to the shift conversion unit. In the steam reformation process, desulphuri- zed naphtha or natural gas is subjected to catalytic reforming in a primary reformer in the presence of steam to form carbon monoxide and hydrogen. Since the reaction is incomplctc in the primary reformer. a secondary refor- mcr is used for converting the remaining hydrocarbons. Air is injected into the secondary reformer to burn the unreatcted hydrocarbons and supply the nitrogen requirement of the raw gas. Coal gasification process involves pulverised coal gasification in the presence of oxygen and steam. The raw gas produced is cleaned up before it goes for shift reaction for purification.

2.1.1.2 Purification of raw ~cy~~--- The first step in the purification of raw synthesis gas is the shift conversion of carbon monoxide to carbon dioxide which is accomplished by reacting carbon monc?xide with steam over activated iron oxide catalyst; carbon dioxide thus produced with hydrogen is removed by absorption process by use of scrubbing solutions. The absorbent\ normally used are hot potash activated with arsenic in Vetrocoke

IS:9841- 1981

process. hot potash activated with a small quantity crf vanadium, arsenic, ctc, in the Benfield process, chilled methanol in the Kectisol process. monoethanolaminc process, etc. C’arbon dioxldc is recovered and reused. ‘The residual carbon monoxide is removed by mcthanation or absorbed by liquid nitrogen wash.

2.1.1.3 Ammoniu synt/z(~sis - Pure hydrogen 3nci nitrogen in the requir- cd quantities arc made to react under elzvatcd prcssure and tcmpcrature over activated iron oxide catalyst to protiucc ammonia. The ammonia produced is cooled so that it condenses and is ~ccovc~ed in a liquid-gas separator.

2.1.2 Urea Produdon .--- Urea is the main nitrogenous fertilizer in India. Urea is produced from ammonia and carbon dioxide obtained from ammonia plant normally located at the site of the urea plant. Urea synthesis can he divided into three main sections, namely, synthesis, &composition/ recovery and finishing sections. In the synthesis section ammonia and carbon dioxide are comprcsscd in an autoclave at elcvatcd tcmpcraturc and pressure to form a solution of urea, ammonium carbonate and water. The product stream from the urea reactor is a mixture of urea, ammonium carhamate. water. unrcncted ammonia and carbon dioxide. An excess ol’ ammonia 1s always maintained, so that carbon dioxide concentration in the exit stream is low. The next section. in the urea process is the &composition section whcrc: the solution from the autoclave is hcatcd to decompose ammonium carbamate. The decomposed ammonium carbamate along with excess and unreacted ammonia and carbon dioxide is recycled in the autoclave, while 70 to 75 percent urea solution is recovered. ln the finished section, the urea solution leaving the dccompositi&n section is further processed. The urea solution is concentrated under vacuum or at atmospheric pressure in a specially designed evaporator of falling film type to raise the urea concentration above 98 percent. The molten urea from the concentrator is pumped to the top of the prilling tower where it is sprayed downward against an upward stream of cold air. The urea prills from the tower are cooled, screened and stored.

2.1.3 Ammoniunz Sulphate Prodzzction -~- Ammonium sulphate is produced from three sources.

2.1.3.1 The production of coke from coal results in the production of coke oven gas which contains a significant amount of ammonia. This ammonia is converted into byproduct ammonium sulphate by reacting it with sulphuric acid.

2.1.3.2 Ammonium sulphate is produced by neutralizing synthetic ammonia with sulphuric acid and the ammonium sulphate crystals formed are separated from the mother liquor by filtration or centrifuging.

6

IS:0841 - 1981

2.1.3.3 Ammonium sulphatc is ;~.lso manufactured from natural or byproduct gypsum. The ground gypsum is reacted with ammonium carbo- natc producing ammonium sulphatc and chalk. The chalk is separated by filtration and the liquor is evaporated and crystallized. The ammonium sulphatc crystals arc scparatcd by filtration and dried.

2.1.4 Anunoniur~z hritrutc, and C’dcimz Arnnwniuw Nirratc Production Ammonia reacts with nitric acid in a neutralizer producing ammonium nitrate. Ammonia and nitric acid are prohcatcd with the vapours of the ncutrali7cr. In the neutralizer, concentrated ammonium nitrate solution is producctl which is f‘urthcr concentrated in vacuum concentrators. Ill

ammonium nitrate production, the concentration is carried out up to molten nitrate which is then sprayed from a prllling tower against an upward stream of air to produce prilled ammonium nitrate. In the case of‘ calcium ;tmmonium nitrate (CAN), the concentrated liquor is pumped and sprayed Into the granulator which is also fed with a measured quantity of limestone powder and recycle fines. The hot granules arc dried, scrcencd, cooled and coated with soapstone dust in a coating drum and stored.

2.1.5 Nttric Acid and .Su/p/mu’~~ Ac,iti Pwductior~ In the industries where ammonium nitrate and anlmonium sulphatc are produced, nitric acid and bulphuric acid production plants arc alho installed. Sulphuric acid and nitric acid are also required for the production of phosphatic fertilirers. Nitric acid is produced by oxidation of ammonia over a noble metal catalyst and absorbing III water. Sulphuric acid is normally produced by burning sulphur to form sulphur dioxide which is then oxidized to sulphur trioxide over vanadium catalyst: sulphur trioxide is then absorbed in concentrated sulphuric acid.

2.1.6 Armnonito~l C/dot-i& Production ~-- Ammonium chloride is normally obtained as a byproduct in the production of soda ash. Sodium chloride is reacted with ammonium bicarbonate producing ammonium chloride and sodium bicarbonate. The ammonium chloride solution is filtered, evaporated and crystallized. Ammonium chloride is also manufactured by direct neutralization of ammonia with hydrochloric acid gas.

2.2 Phosphatic Fertilizer Industry

2.2.1 Pkosplwric Acid--- In the manufacture of phosphatic fertilizers, ihe production of phosphoric acid is the basic building block. The first step involved in phosphoric acid production is grinding of rock phosphate. Ground phosphate rock is mixed with sulphuric acid after the acid has first been diluted with water to 55 to 70 percent sulphuric acid concentration. The acidulatcd rock is digested and retained for several hours in attack vessels. The rock phosphate is converted into gypsum and phosphoric acid. Some of the fluorine contained in the rock phosphate is evolved from the attack vessels as silicon tetrafluoride and hydrofluoric acid. Both silicon

IS : 9x41 - 19x1

fluoride and hydrofluoric acid are collected in the wet scrubber unit. Some quantity of fluorine and I’,<), remains along with the byproduct gypsum which posts disposal problems. After the reaction in the digester. the mixture of phosphoric acid and gypsum is pumped to the filter whcrc gypsum is separated from phosphoric acid. ljilute phosphoric acid, thus produced is further concentrated to 40 to 54 percent phosphorus pentoxide under reduced pressure. Iluring concentration. the evolved fluorine together with minor quantities of phosphoric acid passes to the barometric condensers and thcsc contaminate the condenser water.

22.2 Sitrglr .)‘lcp~,rpho.rpll{lt~, -- Single supcrphosphatc is produced by tho reaction of sulphuric acid with ground rock phosphate. After reaction. the mixture is transferred to a den where suthcient retention time is provided for solidification. At the end, it is taken to storage for curing.

2.2.3 Trip/c Slrp~~rph(~.rpi2l~r(’ Ground rock phosphate and phosphoric acid are mixed in a tank with agitation. After reaction the slurry is distributed on to the recycled dry product. It ic dried in rotary driers and Gzed in vibrating screens before storage.

2.2.4 Ammo/lium Pl~osphotcs Two primary raw materi,tls for the production of ammonium phosphates are ammonia and phosphoric acid. Different grades of ammonium phosphate vary only in the mtrogcn and phosphate contents. Therefore, by controlling the degree of ammoniation during the neutralization of phosphoric acid, ditl’erent grades ofammonium phosphate can be obtained. Ammonia is reacted with phosphoric acid in vertical cylindrical vessels with or without agitation. The resultant slurry is then distributed on to dry rccyclcd product. The product is then dischnrgcd into rotary driers from where it passes to storage.

2.2.5 Nitropho.~phrJtc.r - Nitric acid acidulation differs from sulphuric acid acidulation in that phosphoric acid is not separated as a product from the acidulation reaction mixture. Nitric acid and rock phoshpate are mixed in a series of reaction vessels with agitation. In the first few vessels. the reaction products - calcium nitrate and phosphoric acid-remain in a mixed liquid form. At this point. either phosphoric or sulphuric acid is added together with ammonia to produce a specific mix of calcium compounds, ammonium nitrate and phosphoric acid. This is then converted into a dry product.

3. SOURCES, VOLUMES AND CHARACTERISTICS OF EFFLI’ENTS

3.1 Nitrogenous Fertilizer Industry (Sources of Effluents )

3.1.1 Ammonia Plant

3.1.1.1 From raw material handling, storage and preparatron sections. normally a small stream of effluent containing mainly some coal dust, fuel oil or naphtha is discharged, depending on the feed stock used

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IS : 9841 - 1981

3.1.1.2 Where coal is used as feedstock, a considerable qllantit)‘, of quenched ash is discharged continuously from the coal gasification sectron. The ash slurry from the direct scrubber recirculating water settling system containing some cyanides is also discharged to the ash pond.

3.1.1.3 When naphtha is used as feed stock. the chlucnts from the oil gasification section and carbon recycle section contain high concentration of oil, in addition to the carbon particles and sulphidc impurities. Catal! tic steam reformation process is mostly adopted when naphtha i4 USC{! nc feedstock. No liquid effluents are produced in this process.

3.1.1.4 In the partial oxidation process. finely divided carbon is proJucc~~ Some built-in facility in the plant exists for recycle and reuse of this wrhor in the process itself, but due to unforeseen accidental failure of the $!stcr;‘. some carbon slurry may be discharged for a short period. This carhcm slurry may also contain some cyanides and sulphides.

3.1.1.5 Depending on the absorbent used for the purification of raw ga>. some toxic chemicals, namely, arsenic, MEA, vanadium, methanol and some alkali are discharged in a small stream.

3.1.1.6 From the CO-conversion unit, some quantity of condensate containing ammonia and catalyst dust is discharged.

3.1.1.7 During the commissioning of the plant and initial start-up some quantity of ammonia is discharged when the catalyst reduction operation is carried out. Normally, this effluent emanates once every 2 to 3 years.

3.1.1.8 From the ammonia synthesis section, a stream of condensate containing oil is discharged.

3.1.1.9 Some effluent containing ammonia is sometimes discharged from the storage and recovery sections of some plants.

3.1.1.10 A continuous purge from recirculating cooling water is discharged which contains conditioning chemicals and biocides.

3.1.2 Urea Plan1

3.1.2.1 From the carbon dioxide compression section some ctfluent containing oil is discharged.

3.1.2.2 Considerable quantities of ammonia and urea arc discharged continuously along with the vacuum condensate. In modern urea plants. the quantities of ammonia and urea discharged has been reduced appreciably be process modification. When urea solution is concentrated at atmospheric pressure, no liquid effluent is produced in the urea plant, as no barometric condenser is needed for vacuum generation,

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IS: 9841 - 1981

3.1.2.3 Some urea and ammonia are occasionally discharged which originate from spillage, leakage of glands, flanges, joints, etc. floor washings and also from drainings during shutdown and startup of plants. In modern plant\ these discharges are collected and rccyled.

3.1.2.4 A stream of cooling water purge containing conditioning chcml- cals and biocidcs is discharged from the cooling tower continuously.

3.1.3.1 The scrubber liquor from the neutralization section contains ammonia and nitric acid which may or may not be recycled.

3.1.3.2 Some ammonium nitrate is discharged from the vacuum concentration section.

3.1.3.3 Occasional spillage and leakage from process may give rise to an cfflucnt containing ammomum nitrate.

3.1.3.4 The cooling water blowdown containing some conditioning chemicals and biocides is discharged continuously.

3.1.4 Amnioitium Sulphtc Plant

3.1.4.1 From the reaction and filtration section of the gypsum process, some effluents are discharged which contains ammonium sulphate, ammonia, chalk, etc.

3.1.4.2 Where direct neutralization is done, a small quantity of ammonia may be released in the efffuent.

3.1.4.3 From the concentration, evaporation and crystallization section, an effluent containing ammonia and ammonium sulphate is discharged.

3.1.4.4 Spillage and leakages also form another effluent stream eflluent containing mainly ammonium sulphate.

3.1.4.5 Cooling tower blowdown containing conditioning chemicals and biocides is discharged continuously.

3.1.5 Amtnotliutn Cltloridcj Plant -- The efBuents are mixed up with soda ash plant effluent and contain ammonia and ammonium chloride. However, this efllucnt is discharged in a limited quantity.

3.1.5.1 In the direct process, the main effluent is the wash water used to wash the gases before they arc let out. This will be of considerable volume aud will contain ammonia.

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IS : 9841 - 1981

3.2 Phosphatic Fertilizer Industry ( Sources of Effluents )

3.2.1 Phosphoric Acid Plant

3.2.1.1 During the digestion of rock phosphate with acid, silica, fluorine and other impurities present in it are evolved as silicon fluoride, hydrotluoric acid, dust, etc. These off-gases are scrubbed with water. A part of the scrubber liquor is discharged continuously.

3.2.1.2 In the phosphoric acid concentration section, fluorine together with minor quantity of phosphoric acid passes to the barometric condenser. The condenser discharge contains 2 to .J.percent H,SiF,.

3.2.1.3 From the gypsum filtration section also, some quantity of effluent is discharged which contains suspended matter, phosphorus pentoxide and fluorine.

3.2.1.4 Normally, the gypsum obtained as a by-product is collected in a pond; the overflow from this pond contains suspended matter, phosphate, fluorine, etc.

3.2.2 Single Sqwrphosphate - During the production of single superphosphate dust, fluorine. phosphate bearing waste water is discharged from scrubbers of the digestion section and scrubber liquor of the exit off-gases from the dens.

3.2.3 Triple Supcrphosphute - In the manufacture of triple superphosphate dust, fluorine, phosphate bearing off-gases from the reaction vessels, granulator and dryer are scrubbed with water. A part of this scrubber liquor finds its way out in the effluent stream.

3.2.4 Ammonium Phosphates --- The main effluent normally discharged from ammonium phosphate plant contains ammonia, phosphate, fluorine, dust, etc. The contaminants indicated above are evolved during the neutralization reaction, and granulation, drying and sizing operations. These off-gases are scrubbed with phosphoric acid and the entire scrubber liquor is put into the reactor.

3.2.5 Nitrophosphates - In nitrophosphate production also, dust, fluorine, phosphate, ammonia, ctc, containing off-gases from digestion and ammoniation section and also from drying, granulation and sizing sections are scrubbed with water for reduction of the pollutants in the emissions of nitrophosphate plant. A portion of the scrubber liquor is discharged as effluent continously.

3.2.6 During the processes of manufacture of phosphoric acid and phosphatic fertilizers considerable quantity of recirculating cooling water is used. A continuous stream of cooling water blowdown containing conditioning chemicals and biocides is discharged from the cooling towers

IS:9841- 1981

3.2.7 Sulphuric Acid Plants - When there are leakages, the cooling water gets contaminated with sulphuric acid.

3.2.8 Nitric Acid Plant -- When there are leakages, the cooling water gets contaminated with nitric acid.

3.3 Quantity of Effluent -- The total quantity of finally treated effluent discharged from fertilizer industries varies widely, depending on the raw material used, the end product obtained and the process adopted for the production of fertilizers. A 1 000 tonnes per day urea plant having recirculating cooling water system and all the auxiliary facilities required for production, generally discharges 8 000 to 12 000 m3/day effluents, while a phosphatic fertilizer plant with recirculating cooling water system and auxiliary facilities and having a production capacity of about 100 tonnes of P?O, per day as fertilizer generally discharges 3 000 to 6 000 m3/day effluents.

3.4 Characteristics of Effluents

3.4.1 The main pollutants from the nitrogenous and phosphatic fertilizer industry along with the auxiliary facilities are indicated below:

a> b) c) 4 4 f > 8) h)

Ammonia and ammonium salt;

Suspended solids and ash;

Acids and alkalis;

Oil;

Arsenic, MEA and methanol;

Nitrates;

Urea;

Cooling water conditioning chemicals like chromate, phosphates, biocides, etc;

j) Cyanides and sulphides;

k) Biochemical oxygen demand;

m) Fluorides; and

n) Phosphates, etc.

3.4.2 Nitrogenous Fertilizer - Typical ranges of contaminant concentra tions* from various operations are given below:

*Data based on Revised Draft Report on Fertilizer Industry Pollution and Contrc Measures submitted to the Central Board for Prevention and Control of Water Pollutio by Tata Consulting Engineers, Bombay.

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IS :9841 - 1981

3.4.2.1 Coohg tower blowdown

a)

b)

c)

4 e> f ) 8)

Contaminant Concentration Range ( mgjl )

Suspended solids 30-3 000

Dissolved solids 300-3 200

Free ammonia 0.4-40

Ammoniacal nitrogen 20-400

Phosphates

Chromium

Chlorides

IO-30

6-R

8-18

20-50

SO-240

Traces

10-I 000

h) Sulphates

j) Calcium

k) Zinc

m) Oil

3.4.2.2 Water treatment plant - _ The effluents from the water treatment ^ -

plant of a nitrogenous fertilizer unit varres from 380 l/tonne ofurea to 2 000 11 tonne of urea, depending upon the quantity of raw water used. The dominant contaminants in a water treatment plant effluent are anions and cations. In a typical nitrogenous fertilizer unit manufacturing urea the amount of sodium hydroxide in the water treatment plant effluent is 11.6 kg/tonne of urea manufactured. The total sulphate ion quantity is 18.2 kg/ tonne of urea. Besides these, when a process condensate is treated for use as boiler feed water, ammonia finds its way into the water treatment plant effluent.

3.4.2.3 Boiler blow-down

Contaminant Concentration Range ( Ifg/J )

.a) Phosphorus 10

b) Dissolved solids 100

c) Suspended solids 10

d) Free ammonia e

e) Ammoniacal nitrogen 2

f) Oil ;0

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IS : 9841 - 1981

3.4.2.4 Ammonia plant

Contaminant

a) Suspended solids

b) Dissolved solids c) Ammoniacal nitrogen d) Arsenic e) Carbon dioxide f) Chlorides

g) Sulphates h) Calcium j) Cyanides

k) Sodium m) Vanadium

3.4.2.5 Urea plant

Contaminant

a) Suspended solids

b) Dissolved solids c) Ammoniacal mitrogen d) Urea

e) Sulphates f) Chlorides

g) Calcium h) Phosphates

Concentration Range ( mg/l )

100-I 5000

1 000-3 000 200-I 500

o-2 5000

SO 200

25 7

75 O*l


100

1000-3 000 500-2 000 340-20 000 200

80 20

5

3.4.3 Phosphatic Fertilizer - Typical ranges of contaminant concentra. tions* from various operations are given below:

3.4.3.1 Cooling tower blowdown

Contaminant Concentration Range ( mg/l ) a) Dissolved solids 380 b) Volatile solids 50

c) Fluorides ( as F ) I

*Data based on Revised Draft Report on Fertilizer Industry Pollution and Contra measures submitted to the Central Board for Provontion and Control of Water Pollutic by Tata Consulting Engincqg,,Bombay.

14

t ;.

IS : 9841 - 1981

d) Chromates

e) Chlorides ( as Cl ) f) Sulphates ( as SO, )

g) Calcium ( as Ca )

3.4.3.2 Boiler blowdown

Contaminant

a) Dissolved solids


9 661 ( fixed )

b) Sulphates ( as SO* ) 918.3-3 813

c) Alkalinity ( as CO, ) 2 150-2 950 d) Hydroxide 450-515

e) Silica ( as SiO, ) 0.80

f) Zinc 0.10

Traces

52 30

10

3.4.3.3 Superphosphate plant

a) b) cl

d)

Contaminant Concentration Range ( mg/l )

Suspended solids 150-6Qo Dissolved solids 644-980 Biochemical oxygen demand 35-175 ( 5 day at 20°C ), Max

Fluorides ( as F ) 1 920-2 163 e) Chlorides ( as Cl ) 42-234 f) Sulphates ( as SO,,) 40-336 g) Calcium 32-86 h) Phosphates ( as PO,) 0.4-l

3.4.3.4 Blending unit

Contaminant Concentration Range ( mg/l )

a) Total dissolved solids 1480 b) Dissolved oxygen 6.7 c) Biochemical oxygen demand 1

( 5 days at 20°C ), Max

d) Chlorides ( as Cl ) 488

15

IS : 9841 - 1981

c) Sulpllates ( as SO,) 200

f) Ammoniacal nitrogen 10

g) Phosphates ( as PO, ) 5

h) Oil and grease Traces

4. METHODS OF TWLATMENT, UTILIZATION AND DISPOSAL

4.1 Ccncrsl --- In the preparation of any scheme of treatment for effluents it is essential that each source of eftluent be studied regarding its flow over a 2J-hour period for several davs and the maximum, minimum and average flow be ascertained. Installation of flowmeter or weir of continuous recording type 1s weful. Otherwise, readings of Aow have to be recorded at hourly intervals normally. In case no measurement device can be installed, the efhuents should flow to a holding tank where the level has to be recorded hourly. While locating the source of effluent, due consideration should be given to occasional discharges due to leakage and Boor washings, etc, and also the ctlluents which may be discharged during malfunctioning of the plants and during the start-up or shutdown of the plant.

4.1.1 I.,ach elfuent source has to be analysed individually over a 24hour period with samples drawn hourly. The samples may be collected hourly and made into 3 to 6 composite samples, depending on the variation of flow and composition.

4.2 Segregation of Effluents The effluent streams have to be segregated according to the nature of pollutants present in them and their concentration. As a general practice, all effluents containing high concentration of total ammonia nitrogen should be combined. Normally eflluent containing ammonia nitrogen above 100 mg/l should fall in this category. However, effluents with 50 to 100 mg/l ammonia nitrogen may also be collected in this stream if the volume is large. The following steps should be followed, wherever applicable :

4

b) c>

4

4

f ) g)

Effluents containing suspended solids above 100 mg/l should be combined together as far as practicable;

Oil bearing effluents should be combined as far as possible;

Highly acidic and alkaline effluents should be separated from the rest of the effluent streams;

Urea bearing effluents which also contain high concentration of ammonia should be separated from ammonia bearing effluent;

All cooling tower purge water containing chromate, phosphate and biocides should be separated from the rest of factory effluents;

Ash slurry should be separated from the rest of the effluents;

Eflluents containing carbon slurry should be stored separately;

16

IS : 9841 - 1981

h) Arsenic and cyanide bearing eflluents should be stored separately;

j) Efiluents containing fluorides and phosphates are to be segregated from other effluents:

k) Sewage effluents should be treated separately as far as possible and

m) Storm water and drain water should not mix with individual plant effluents.

However, many of the above effluents may be combined, depending on their characteristics. flow and type of treatment to be adopted.

4.2.1 After assessment of the individual effluent streams regarding their volume, pollutant content, frequency of discharge etc. the volume and concentration of various pollutants in the final effluent discharged beyond the factory boundary limit have to be ascertained. These figures along with the prevailing standard of the effluents and the receiving water and also the local regulation will indicate the degree of specific type of treatment of the individual segregated eflluents that will be necessary for adoption for treatment of the effluent. Accordingly, various methods of treatment available arc to be studied to suit the requirements for individual pollutants. Once the treatments for the pollutants are finalized, a broad scheme is developed and in the same scheme integration of all the treated effluents is made ( Fig. I ).

4.2.2 While studying the different treatment schemes. preference should always be given to such schemes where some recovery of waste products for reuse in the process or recovery for direct marketing can be made from the wastes. Sometimes the effluent water after adequate treatment can be recycled in the process. This reduces water consumption as well as the final effluent volume discharged.

4.2.3 Sometimes the segregated cthucnts can be combined in such a way that one can be utilized for the treatment of the other. This type of judicious combination reduces the cost of chemicals and also increases the efficiency of’ treatment rendered.

4.2.4 The various processes available at present for the treatment of individual pollutant parameters relevant to the fertilizer industry have been compiled below for study before final adoption according to the suitability of a particular process depending on the degree of treatment considered necessary.

4.3 Treatment of Effluents for Specific Pollutants

4.3.1 Amtnonia NitrL?+ztr Various processes have been developed for removal’recovery of ammonia nitrogen from effluents. These processes basically fall in two categories : ( a ) Physio-chemical. :.nd ( b ) biological.

17

PROCESS WATER TREATMENT PLANT

SULPHURIC ACID PLAN1

7

’

HANDLING SECTION

GENERATION

uNCON

TED E STREA

17 18 19

Y

II9 20 21

r-

13 15 ‘riJ ' 16 I

II,

In

0 yJy7 q ;;$T&E NT 1 1 TO RECE!VI:IG

WATER

FK. I A TYPICAL EFFLUENT TREAThlENT SCHEME OF FERTILIZER FACTORY PRODLTISG UREA AND

PHOSPHATIC FERTILIZERS

1.

2. 3.

4. 5. 6.

7.

8.

z 9.

10. 11. 12. 13. 14. 15. 16. 17. 18. 19.

5:. 22: 23.

Efluent Streams Effluent containing suspended carbon, cyanide, sulphide, etc Condensate containing oil Cooling tower blowdown containing CrO, and PO, Process condensate containing ammonia Catalyst reduction NH% Reactor draining, overflow of tanks and plant washings Vacuum condensate containing ammonia and urea Cooling tower blowdown containing CrO, and PO, Condensate containing oil Acidic effluent Alkaline effluent Acidic effluent Raw water treatment plant sludge Boiler blowdown Ash slurry Oily effluent Concentrated fluosilicic acid solution Effluent containing fluorine and phosphate Gypsum slurry Effluent containing fluorine and phosphate Sewage effluent from toilets and washings Uncontaminated effluent stream Final effluent of the factory after treatment

1.

2.

3. 4. 5. 6.

7. 8.

9.

10.

11. 12.

13. 14.

15.

16.

17.

18.

Treatment of Efluent Suspended matter settling Cyanide, sulphide removal system

Oil separator

Evaporation of ammonia Collection pit for ammoniacal effluent Air/steam stripping of ammonia with recovery of ammonia in case of steam stripping Thermal urea hydrolysis ammonia recovery Chromate phosphate removal system

Neutralization

Oil separation Ash settling pond Oil separation Recovery of fluosilicic acid

Fluorine and phosphate removal system

Gypsum settling pond

Sewage treatment

Biological treatment

Mixing pond

IS : 9841 - 19x1

a) Air stripping -~ The concentration of ammoiGa nitrogen in effluent can be reduced considerably by adopting air strIpping of ammonia from the effluent at an elevated pH Ammonium ions ( NH,’ ) in water exist in equilibrium with NH, as follows:

NH,+ =: NH,”

At pH level above 7.0, the equilibrium is shifted progressively towards the right, so that ammonia is liberated as gas. This dissolved gaseous ammonia in the effluent is stripped off by Aowing air through the ellluent.

In actual operation, the pH of the waste water is brought to a pH lcvcl between IO.0 and 1 I.0 by adding alkali; the waste water is then pumped to the top of the cooling tower type packed tower and distributed evenly to cover the full surface of the packings ( k:ig. 2 ). The waste water moves down through the packing countercurrent with the air flow. The tower for ammonia stripping may be either crossflow or counterflow type with induced or forced air circulation. The ammonia present in the waste water is stripped off before it leaves at the bottom of the tower. The extent of ammonia removal depends on many factors of which pH. temperature, ammonia concentration. contact time with air and water-air-water ratio, etc, are very important and these factors are to be considered adequately while designing an air stripper for ammonia removal. In a well designed plant, the concentration of ammonia in the effluent can bc reduced to 50 mg/I adopting this process.

b) .Sf~unz stripping - Steam stripping of ammonia ( Fig. 2 ) is a well established process. The process is adopted by the coke-oven industries for the recovery of by product ammonia.. Here also stripping of ammonia from waste water depends on how the ammonia exists in the water. In neutral solution, ammonia does not exist as dissolved NH, gas at ambient temperature. Therefore, the pH and the temperature are increased, so that the reaction proceeds progressively further to the right, namely, in favour of the formation of NH,. In a suitably designed distillation unit, the ammonia can be stripped OR by steam with or without raising the pH as the case may be and the resultant ammonia can be covered by condensing as dilute ammonia solution or as ammonium sulphate solution after neutralizing it with sulphuric acid. Under ideal operating conditions, 90 to 99 percent ammonia removal efficiency can be obtained.

c) /on exchange - Ion exchange is a unique eflluent waste water treatment method. Ion exchange can accomplish purification of tha

20

AIR AMHONl A

AMMONIACAL WASTE CLARIFICATION

EFFLUENT ALKALI STREAM

I

i J

FIG. 2 AMMONIACAL EFFLUENT TREATMEST

I SLUDGE

BY STEAM/AIR STRIPPING

IS : 9841- 1981

waste water to a quality that could comply with zero pollutant discharge criteria or that would permit complete recycle of waste waters. The ion exchange process can also accomplish complete recovery of waste products bein? lost along with the waste water stream and can provide for efficient recycle of the recovered products into the plant proccssc\. This may be reprcscntcd as follows:

I NH,NO,, 7

HNO, ]

> H,SO, J

R,SO,, j

/- HNO, + RH _- - RNH, + {

t H,SOI

f N&NO, + RNH,--:- RH + (

1 (NH,), SO4

r RNO, +- ROH -+ H,O + (

( R,SO,

[ NH,NO, + NH, OH -a ROH .: {

((NH,), SO,

When the recovery of ammonia by ion exchange is aimed at from amlnoniacal waste waters and no recovery of waste water is envi- ‘raged . :t simple process based on adsorption of ammonium ion by hydrogen form 01’ a cation exchanger is incorporated ( Fig. 3 ). The clarified ammoniacal waste water is passed through the exchange column whcrc ammonium ion would be absorbed in the exchanger replacing hydr-c~gcn ion. When the exchanger approaches exhaus- tion ( indicated 12) residual ammonium ion in the treated ettluent at the outlet of‘ fh~ cxchangcr ), it is regenerated to the hydrogen form with a suitable concentration of sulphuriqnitric acid. The regeneration procchs i\ adopted to get minimum regenerant use and maximum concentration of product solution. The product ammonium sulphatc or amlllonium nitrate solution is concentrated and pruccsscd in the process plant for the production of fertilizer and the waste water with ver) low concentration of ammonia is neutralized before discharge along with the other eflluent streams.

When the recovery of waste water is also envisaged, in addition to a cation exchanger. an anion exchanger is incorporated ( Fig. 4). This unit can be used for the treatment of waste waters containing both ammonium ions and other acidic ions. The ammonium salt contaminated waste water after proper clarification first flows through a bed of strongly acidic cation. resin operating, in the hydrogen form. The ammonium ion combines with the catlon. while the hydrogen ion combines with the nitrate/sulphate ion to form nitric/

22

IS : 9841 - 1981

ACID

7 AMMONIACAL

FILTRATION DISPO~

EXCHANGER NLlJTRALIZ4TlON

EFFLUENT

t ;r 4MMONIUM SALT SOLUTIOV

FIG. 3 AMMONIACALEFFLUENT I'KEATMENI. 1%~ CATION EXCHANL~

sulphuric acid. The acidic water then passes through the bed of anion resin in base form where the acidic ions are absorbed. The effluent water from the second bed is very low in ammonium salts. and can be reused in the process as make up water in boiler feed water treatment plant and may be used in the boilers after polish- ing in mixed bed ion cxchangc system. The cation exchange resin holding the ammonium ion can be regenerated using sulphuric or nitric acid to form ammonium sulphate or nitrate solution. The anion resin holding the acidic ion is regenerated using a solution of ammonium hydroxide to form more ammonium sulphate or nitrate solution. The ammonium salt solution thus produced may be used in the process for the production of ammonium sulphate or nitrate, provided such facilities arc available at site. It may be noted that soluble inorganic contaminants in the waste water will also find their way into the product.

4.3.1.2 Biolo~icd proccsw Y

a) Biological nitrijicutiotz ailrick~nit~L~catiorr -~ Biological nitrification and denitrifcation can reduce ammoniacal nitrogen content of the final effluent to a very low level. This process is being adopted in municipal waste treatment for years. In the treatment of industrial waste, this treatment may be adopted as a secondary or tertiaq treatment where the ammonia nitrogen content of the influcnt is comparatively low and also a high degree of treatment for the removal of ammoniacal nitrogen is desired.

The treatment is based on the reaction of ammonia nitrogen wjt:l oxygen in an aerated pond or lagoon to form nitrites and linally to the nitrate nitrogen form in the presence of a specialized group P(

IS : 9841 - 1081

nitritymg organisms ( Fig. 5 ). The mtrates irl turn rcact~d I,)

another anaerobic pond in the presence 01‘ biodegradable carbon compound employing the denitrifying process I‘orm elemental nitro-

gen. The process may be rcprcsented as follows:

Ammonia Aeration Nitrate Organrc nitrogen nitrogen carbon

--- + N lJ Nitrifying I)enitrifyin;

(‘0,

organism organism

The first step nitrification takes place in the presence of acrobrc bacteria which converts the ammonia nitrogen into nitrates. 7311s reaction is affected by degree of aeration, water temperature, lmtral ammonia nitrogen content. bacterial population, ptl of solution. etc. As destruction of alkalinity is associated with the reaction. sufhcicnt alkalinity should be present in the waste in the nitrification tank, otherwise alkalinity should be supplemented to the waste water. Similar supplementation may be required for other bacterial nutrients like phosphate, potassium, magnesium, iron, etc if these arc not originally present adequately in the waste water. This \tep can be carried out in tank. pond. lagoon, trickling filter. etc.

The denitrification step is an anaerobic process which occurs when the biological micro-organisms cause the nitrates and the organic carbon to be broken down into nitrogen gas and carbon dioxide. As the organisms responsible for denitrification can utiliLc only organic carbonas their carbon source, a supplement of a readily biodegradable soluble organic compound is required to be added to the nitrified e@luent prior to its entry into the denitrification unit. The organic carbon used for such a process is methanol, sewage effluent or organic waste from industries. In case methanol is used as the organic carbon source, 2 to 2.5 g of methanol is required for denitrification of lg of nitrate nitrogen. This reaction is carried out in a tank, pond or lagoon under anaerobic conditions. The reaction requires very low or nil dissolved oxygen in the effluent, neutral pH range, proper supply of organic carbon, suitable detention time, etc.

b) Al& uptake -- Since ammonia nitrogen is an algal nutrient, algae are capable of extracting this nutrient from the waste water. Algae growing in waste water stabilization ponds utilize ammonia nitrogen of the waste water to form cell tissue in the presence of sunlight. Adequate carbon dioxide and some other nutrients are also required in this process. For fixing up Ig of nitrogen into algal cell material 10 to 12 g of carbon as carbon dioxide gas is normally required.

ORGANIC C+‘.-130’1 - ._~__ .---. ~_. _--_c -(SEWAGE J h!E’>I,jL!,L)

NUTRIENT

ALKALi

AMt.:ON!ACAl. EFFLUENT o----- ORGANIC CARBON -___

(SEWAGE/ METHANOL)

1

NlTRATf BEARING EFFLUENT e

FIG. 5 DILUI-E AMMONIA AND UREA BEARING EFFLUENT TREATMEN

r_lli Cl_Ai?iF~i?.i CIr:

IS : 9841 - 19x1

Oxidation pond-like ponds may be used for the culture of algae (Fig. 6). Carbon dioxide may bc supplied by biodegradation of organic matter or dilute carbon dioxide may be dil~us~d through a network of carbon dioxide difTuscrs in the pond. Other ncccssary nutrients for algal cultures may be supplemented in the pond. With suitable detention t&c, depth of the pored. conccntmtjon of algae, concentration of ammonia nitrogen, sunlight. etc. the upt:tkc of ammonia nitrogen in the cell formation of algal cell> is quite appreciable. Algae thus produced may be harvested u>ing a suitable process and utilized as manure.

4.3.2 Urm and Nitrate Nitropv~

4.3.2.1 In modern urea manufacturing technology, thermal urea hydrolysis with recovery of ammonia of the waste water ( f-‘ig. 7 J is being incur- porated in the plant itself. This system, if provided. is expected to reduce the quantity of urea in the effluent appreciably. The use of hydrolyser stripper should bc considered as an alternate arrangement.

4.3.2.2 Urea nitrogen can be removed from clfucnts by h;drolyJing urea in the presence of enzyme urease secreted by some bacteria formed in the soil (Fig. 5). The dilute urea solution i\ hydrolyred by the abate bacteria in the presence of organic carbon compounds to give ammonia and carbon dioxide.

NH,CONH, -I- 2H,O + (NH,),CO,

The pH increases with the progress of hydrolysis; under properly maintained conditions, over 95 percent of urea can be hydrolyzed in 2-t h. The hydrolyzed solution containing ammoniacan be treated by any of the methods described under ammonia removal.

4.3.2.3 Reduetion of nitrates can be clfected by the dcnitrilication process (Fig. 5) described under 4.3. 1. 2 (a).

4.3.3 Sqxwdetl Solids - Suspended solids originate from various sources in the fertilizer industry. The process water clarification plant sludge. aah slurry from coal gasification plants, steam generation plants or phosphoric acid plant effluent during neutralization of effluent with lime, etc. suspc~~cled solids in different particle sizes find their way into the eflluent. I IlCX effluents containing suspended solids are settled in a suitably dcs~gncd wtt-

ling basin and the clear overflow passes out. In home case\. pat :iLularlq where the particlc size is comparatively small. mechanical clar~fi~rh ha\ 1n.p proper arrangements of dosing coagulants or polyelectrol> tcy art‘ rcquircti for quick settling. The sludge discharged from the bottom of the clarifier may be dra\vn out mechanically, dewatercd and disposed of as solid waste as required.

27

IS : 9841 - 1981

4.3.4 pH-Sometimes the effluents are highly acidic or alkaline in nature. When both acidic and alkaline waste waters are found, they may be mixed suitably for neutralization. Otherwise for neutralization of acidic effluent, lime or soda ash may be used and for neutralization of alkaline eflluent sulphuric acid may be used. In the process of neutralization proper mixing is very important. This can be effected by flash mixing or mixing by agitation or recirculation.

4.3.5 Oils ad Greases - Oils and greases normally discharged in fertilizer industry eflluents are mostly in non-emulsified form. Furthermore, a majority of these insoluble oils are lighter than water and therefore they will float on its surface. Insoluble oils lighter than water are usually separated in settling tanks provided with an adjustable skimming weir (Fig. 8). These settlers are usually termed as gravity type mechanical oil separators. The oils readily float on these separators and the depth of the weir is adjusted according to the amount of oil present in the waste water. The collected oil is skimmed by mechanical means periodically. A properly designed oil separator can reduce the oil content of the effluent below 50 mg/l. If a greater degree of oil removal is desired, the effluent from the oil separator may be passed through active carbon or a porous coke bed by which the oil and grease content of the effluent is reduced to 3 to IO mg/l.

4.3.6 Atwnic -- In fertilizer industry, arsenic is a constituent ofabsorbent liquids used for carbon dioxide removal. Normally adequate arrangements are provided in the plant so that arsenic does not find its way out in the eflluedt. But in actual practice, due to leakages in pump glands, flanges, joints, etc, and also from spillages, some arsenical solution is discharged. The quantity of this arsenical solution can be controlled within reasonable limits by good housekeeping. The arsenic solution which is discharged even after taking all the precautions is completely separated from other waste waters. The waste water containing arsenic is then filtered, concentrated, further filtered through active carbon filter if necessary and recycled in the process. When it is not possible to take it into the process, the arsenical solution is evaporated to dryness and the solids are placed in con- crete drums, sealed properly and buried underground or disposed of into the deep sea far away from the coastline.

4.3.7 Cltrotttate atd Phosphare -- Fertilizer industry requir-es a high quantity of cooling water during processing of fertilizers. In most of the fertilizer factories. cooling water is recycled through cooling towers. Suit- able inhibitors for control of scaling/corrosion properties of circulating water are dosed into the cooling water system. Various inhibitors are used depending on the local conditions. Most of the plants use combinations of chromate, phosphate and zinc in different proportions. Normally. zinc is used in a very low concentration, therefore, any specific treatment for the removal of zinc is not considered necessary. In the treatment for removal of chromate

29

IS : 9841 - 1981

from waste water, phosphate is also simultaneously removed, so specific treatment for removal of phosphates is not considered necessary.

The basic principle of chromate removal is the reduction of hexavalent chromium to trivalent form and precipitation of chromium as chromium hydroxide (Fig. 9).

REDUCING AGENT FERROUS SULPKATE/S001UM SULPHI’I+/

MEiStiLUC2llE I $:.LP:!~‘II OIOX.!DE

C ACID

LIME -

CGOLtNG TOWER BLOWDOWN

AND PHOSPHATE

t

ACID NEUTRACIZATIClN

SETTLING D’spos2

/

1 SLUDGE _

FIG. 9 CHROMATE BEARING EFFLUENT TREATMBNT

The cooling tower blowdown which contains chromate is collected in a tank and the%pH of the water is lowered to the range 2 to 4 by adding sulphuric acid. After mixing with the acid, ferrous sulphate, sodium sulphite, sodium metabisulphite or sulphur dioxide is added to reduce hexavalent chromium. For removal of lg of CrO, about 10 g of ferrous sulphate, 2.5 g of sodium sulphite or 1.5 g of sulphur dioxide is required. After reduction, lime is added to the effluent for raising the pH and precipitation of chromium. The settled effluent is allowed to be discharged along with other effluents of the factory. The reactions which take place during the above operations are as follows:

Reduction of chromate

1, When ferrous sulphate is used for reduction:

Na,Cr,O, + 6FeS0, + 7 H,SO, ----f Cr,(SO& + 3Fe,(SO,), + 7 H,O + Na2S0,

2. When sodium sulphite is used for reduction:

Na,Cr,O, + 3Na,SO, -I- 4H,SO, -+ 4Na,SO, + + 4&O

3. When sulphur dioxide is used for reduction:

Na,Cr,O, + 3S01 + HpSO, ---+ Cr., (SO,), + HI0 + Na,SO,

31

IS:9841-1981

Precipitation with lime

Cr,(SOJ, + 3Ca(OH), -+ 2Cr (OH), + 3CaS0,

Fe,(SO.& + 3Ca(OH), 4 2Fe (OH), + 3CaS0,

Lime treatment for precipitation of chromium also partially precipitates out phosphate which is added to the cooling towers as sodium hexameta- phosphate.

Recently, another iron process based on reduction with ferrous ion provided by electrolysis using iron electrode has been developed. This process can operate at pH 6 to 8. The chromium hydroxide and iron hydroxide are precrpitated together and can be separated as a sludge by clarification. It consumes only electricity and metallic iron.

4.3.7.1 Many fertilizer units use furnace oils containing about 4 percent sulphur in their boilers; the boiler stack contains around 0.2 percent SO, which is a reducing agent. The chemistry of the process is:

Cr,O, + 3S0, -t 2H+ -+ 2Cr+-++ + 3SO,-- -1 HZ0

The reaction takes place quite rapidly at low pH (2 to 3). The SO, present in the flue gas helps in attaining the low pH of this order; under this condition even a small percentage of SO, is able to reduce the hexavalent chromium. In this arrangement the problem of air contamination is also reduced due to utilization of SO, and SO,.

The resulting trivalent chromium as chromium sulphate is much less toxic. To fully overcome the toxicity problem, it is necessary to convert soluble chromium sulphate into chromium hydroxide atpH 10 to 11 through the addition of alkali as suggested in 4.3.7. However, to further reduce the cost of disposal, the ammonia containing waste water itself may be utilized as an alkali to bring about the precipitation of chromium hydroxide. Effluents from fertilizer plants happen to be rich in plant nutrients and can be a secondary source of fertilizers. These effluents can, therefore, after suitable treatment, be applied on land for irrigation with the prior permission of local authorities. Experiments have shown that the etfluents from fertilizer plants can be usefully employed to raise various crops and vegetables due to their high nitrogen and phosphorus contents.

4.3.8 Cyanide - Depending on the process and raw material, cyanides are sometimes encountered in the fertilizer factory effluent. Usually cyanide containing effluents are completely segregated from other waste waters and are treated or disposed of separately. When the cyanide content is low, the effluent can be discharged at a controlled rate along with the other waste water, so that cyanide content of the final effluent does not go beyond specified limits. When the cyanide content of the effluent is comparatively high, some suitable treatment is required.

32

1s: 9841 - 1981

4.3.8.1 When cyanide content is high and the etiluent volume is low it can be removed by stripping with steam and acidic gas (Fig. IO). The residual cyanide after stripping may be treated further. if required.

STEAM AND-/OR SODIUM _ SODIUM

ACIDIC GAS HYDROXIDE

1 I I 7

1 ,

CYANIDE BEARING PARTIAL COMPLETE

EFFLUENT -STRIPPER 7 OXIOATION r_ OXIDATION

’ TO CYANATE TO NITROGEN DISPOSAL

i /

1 i_ _?.?PO_S!J- __

FK. 10 CYANIDE BEARING EFFLI.IEN.T TRFATMEN~

4.3.8.2 Cyanide bearing effluents may be treated by alkaline chlorina- tion process ( Fig. 10 ) which oxidizes cyanide ultimately into carbon dioxide and nitrogen. Cyanide forms cyanogcn chloride according to the equation:

NaCN ;- Cl, - > CNCl .:- NaCI.

In the presence of caustic soda cyanogen chloride is converted into sodium cyanate a> follows:

CNCl -t 2 NaOH -+ NaCNO + HZ0 + NaCl

The sodium cyanate produced in the above reaction is much less toxic and may be discharged along with other effluents. If complete treatment is desired, sodium cyanate is further oxidized by the addition of chlorine to carbon dioxide and nitrogen.

2NaCN0 + 4NaOH f 3C1, --f 2C0, + 6NaCl + N, + 2H,O

In order to have simplified operation and control, a single vessel is used for cyanide removal. The pH is maintained at about 8.5 by dosing caustic soda, and chlorine is added from chlorinators of suitable capacity. The requirement of chlorine for complete oxidation of cyanide is 9 to 10 g for 1 g of cyanide. The process is quite satisfactory for treatment of efhuents from fertilizer industries.

4.3.9 Sulphides - Sulphides are sometimes present in small quantities in fertilizer factory effluents. Water containing sulphides in excess of 0.5 mg,‘l has offensive ( rotten egg ) odour and is also very corrosive. The sulphides

33

IS : 9841 - 1981

present in fertilizer factory waste water normally do not require any special treatment. Natural dilution by the other waste water from the factory is sullicicnt to bring down the level ofsulphides within specified limits. Sulphi- Jcs are present in acidic pH range as hydrogen sulphidc and in ALaline pII range as sulphidc salts. Hydrogen sulphide is usually removed by acr;t- lion process in the acidic pH range. In this process hydrogen sulphidc removal 15 by stripping rather than oxidation. Sometimes chemical oxidation by dosinS chlorine is also resorted to for removing sulphides from effuents.

4.3.9.1 Sulphidc\ can also bc prccipitatcd chemically.

4.3.10 L‘lfloritk~s tr~l Phosp/raf~~v The main source of fluorides and phos- phatcs in the phosphatic fertilizer industry are scrubber liquors from various unit opcratiom involving scrubbing of the off-gases. floor ivashings and ~~~psurn md water. In the clllucnt. fluorides are present as fluosilicic acid bith smail amounts of soluble salts as sodiutn and potassium fluocilicatcs and hydrofluolic acid. Phosphorus is present principally as phosphoric acid with minor amounts of soluble calcium phosphates. For the removal 01‘ Fluorides and phosphates two-stage treatment with chalk f~~llowed by lime or tioublc lime treatment is adopted ( Fig. 1 I ).

cA~c1ut.4 CARBONATE LIME

-mz--l 1 ? ? _ t

FLUORIDE AN0 FIRST SECOND PHOSPHATE ) STAGE _ STAGE

REACTION REACTION

EFFLUENT TANK TANK

I-I(,. I I FLUOK~E AND PHOSPHATE BEARING EFFLUENT TREATMENT

In the former case, in the first stages the effluent is treated with chalk or finely divided calcium carbonate at a pH of about 3.0. The requirement of calcium carbonate is 3 to 3.5 g for I g of F and 0% to 0.7 g for I g of PO,. The following reactions are believed to take place:

H,SiF, -I- 3CaCO,, -+ 3CaF, -+ SiO, + 3C0, -t H,O

?H,PO, + CaCO, + Ca ( H,PO, ):: + H,O i- CO,

In the above reactions, almost all the fluorides arc precipitated ac calcium fluoride. Silica is also precipitated out. However, most of the phosphates remain in solution as monocalcium phosphate. During the second stage treatment, the product of the first stage is further treated with lime at a pH

33

1s: 9841 - 1981

of about 8.5. In this reaction. calcium hydroxide requirement is 2. I to 2.3 6 for I g of residual F and 1.0 to 1.1 g for I g of residual PO,,.

It is believed that in the second stage the undermentioned reaction takes place:

H,SiF, + 3Ca ( OH j2 -+ 3CaF, -t SiO, -t 3H,O

3Ca ( H,PO, )z + 7Ca ( OH )z -+ 2Ca,OH ( PO, )s + I2H,O

In the second stage. residual fluorides and phosphates from the first stage arc converted into insoluble caicium fluoride and calcium hydroxy apatite at /IH around 8.5 and precipitated out. The overall fluoride and phosphate removal efficiency is above 99 percent in the above two stage treatment.

In double lime treatment, lime is used in place of chalk or powdered calcium carbonate as indicated earlier in the two stage treatment.

The efhuent after the second stage reaction is transferred to a settler for the removal of fluoride and phosphate precipitates and the overflow water is discharged. The settled sludges are removed periodically and dumped or used as fill for low lying areas.

4.X10.1 Where by-product precipitated chalk from ammonium sulphate produced by Merseburg process is used for preliminary treatment, the chalk should have a minimum optimum ammonia level or preferably it should be fret from ammonia.

4.3.11 Srwuge Ejhent .~ The waste water from toilets and other sanitary facilities in the factory area has high biochemical oxygen demand ( BOD ) and contains suspended solids. The sewage effluent is segregated from other industrial wastes and treated for removal of BOD and suspended solids. The volume of the eflluent is normally comparatively low. The general practice is to treat these effluents in oxidation ponds or by aeration processes. How- ever, depending on the level of HOD, these waste waters may be subjected to partial BOD removal by any conventional practice and discharged along with the other treated industrial waste water so that the BOD value of the final effluent does not go beyond specified limits.

4.4 Sampling and .4nalytical Control - In order to observe the performance of the ctlluent treatment units and also to control the plant operating system etfcctivcly. suitable instrumentation for recording pollutants and other physi- cal characteristics ( namely temperature, pressure. flow of effluents, quantny of treatment chemicals. etc ) are required to be incorporated into the etlluent treatment process design. so that input and output conditions of cfhucnt treatment units can be assessed properly. Where suitable automatic continuous monitoring of pollutants in the effluents cannot be provided. regular sampling and anaI!sis of the pollutants necessary for the control of operation arc to be conducted. In such a case, the frequency of sampling and analysis

35

IS :9841- 1981

will depend on the process plant operating conditions but a minimum of two composite samples should be analysed daily. In the case of final effluent discharged beyond the factory boundary limit, a suitable arrangement for recording the volume and proper sampling of the final effluent is to bc made Installation of an automatic pollutant monitoring and recording system for final effluent of the factory is very advantageous and an endeavour should be made to install these instruments wherever possible. Similarly, a composite sample of the receiving water should also be analysed daily. In case some other industries are located on the upstream of the river and they also discharge some effluents to the same river. sampling and analysis of the receiving water should be done. both from the upstream and downstream of the effluent outfall. This will indicate the contribution to pollution by the fertilizer industry concerned.

4.5 Waste Utilization - Apart from the utilization of waste waters and reuse of treated effluents for conservation of water as well as for other purposes, recovery of usable products present in this waste water has gained importance in recent days. The main recoverable products from waste waters of fertilizer industries are ammonia, urea, carbon, fluoride, gypsum, phosphate, chalk, etc, depending on the product manufactured and the process adopted.

4.5.1 Ammonia-The processes commonly used for the recovery of ammonia from ammoniacal waste waters are steam stripping and ion exchange system. Steam stripping of ammonia is suitable for ammoniacal effluent containing high concentration of ammonia with comparatively low volume. The stripped ammonia gas is either absorbed in acid to form ammonium salts or condensed to form ammonia liquor which is recycled in the process itself. In the case of ammoniacal waste waters containing low concentration of ammonia, ammonia can be recovered using a cation exchange system regenerated with acid to produce ammonium salt solution. This process is more suitable where already a secondary ammonium salt manufacturing facility exists.

4.5.2 Urea - In spite of improvement in the design of the urea manufacturing process, substantial amount of urea along with ammonia finds its way into the waste waters of urea plant. The different methods of recovery of urea from these effluents are as follows:

a)

b)

4

Thermal hydrolysis of urea present in the condensate followed by stripping of the ammonia produced and recycling of the ammonia in the urea process itself;

Collecting of all spillages, leakages and overflows of urea bearing waste, concentrating and recycling them in the urea process; and

Scrubbing urea dust from prilling tower exhaust vapours and recove- ring this urea as per process mentioned in (b) above.

36

is: 9x41- 1981

In modern plants all or some of the above processes form an integral part of the urea plant itself and fhc etiluent which comes out from urea plant contains practically a negligible quantity ofurea. In older plants installation of the above facilities is dilficult. as it requires large invcstmcnt. :“&o. thtrc arc constraints in accommodating this additional load in the process. II1

any case installation of these facilities for the recovery of urea improves process eficiency by reducing the specific ammonia consumption. The cost of ammonia recovered by thi5 process is enough to pay back the capital invested in a short time.

4.53 Cc~rhorz - In the partial oxidation process of ammonia manufacture. the carbon formed in the procchs is normally thrown out as carbon slurry. This carbon can bc recovered either by pelleting with a suitable pctrolaum distillate followed by further processln g or by filtration and drying. The recovered carbon has very low particle diameter, large surface area, high covering power and adsorption capacity. It can bc: used as carbon black suitable for printing ink, rubber, battery and other industries. It can also be further processed into active carbon.

4.54 L‘lozlrirl? - The ef’Huents from phosphoric acid plants contam vary- ing concentration of fluoride which pollutes the water course seriously if not removed prior to its discharge. Fluoride is now rccovcrcd from the fluoride bearing cttluents by treating them with lime to recover calcium fluoride, wrth aluminium salts to recover aluminium iluoride and with sodium salts to rccovcr sodium fluoride. Various processes are available for the recovery of fluorides that serve as r,lw material for the manufacture of a wide range of fluoride chemicals.

4.5.5 Gy~~swr -- Gypsum obtained as a byproduct durmg the production of phosphoric acid used to bc dumped in low lying areas. This gypsum can bc processed for various products like ammonium sulphate by Mcrsburg process, plaster boards, and building blocks; it can also be used for land reclamation and recovery of sulphur with simultaneous manufacture of cement.

4.5.6 C/zulk - The chalk is obtained as a byproduct in ammonium sulphate production using Mersburg process utilising gypsum. This chalk is used as a raw material in the manufacture of cement. It is also used to a large extent in neutralizing acidic effluents in industry.

4.57 Pllospllati ~- Substantial amounts of phosphates are present in waste waters of phosphatic industries; these are normally removed during the removal of fluorides. This phosphate can be used in phosphoric acid manufacture after blending with rich rock phosphate. The phosphate bearing sludge can also be used as low nutrient value cheap fertilizer in some cases.

4.6 Disposal - The final disposal of the treated effluents beyond the factory boundary limit is an important step. Normally, effluents originating from

37

IS : ‘)x41- 1981

individual clllucnt treatment units are Icd to a mixing pond. ‘l‘hc uncon taminatcd effluents which do not require any treatment also flow to this mixing pond. It is preferable to give sulficient detention time in Ihi, mixing pOJld for CqualiZatiOIi and alSO t0 effect 5eCOndary settling Of sM;)Cl&xi

matter. The overflow from this final mixing pond passes to the elllucnt drain leading to the receiving waters. It may be clearly understood that the treated effluents in the effluent drain conform to IS : 2-M* and therefore cannot normally be used as raw water source. in case the drain passes through a locality where there is possibility of use of this water as raw water source by the inhabitants and cattle. suitable protection of the drain from the approach of the pcoplc and cattle with proper warnings has to be made. III

some cases it is preferable to discharge the treated effluents through a pipc- lint to the receiving water. When all the characteristics of the individual effluent streams of the process plants are properly asscsscd, the effluents discharged from effluent treatment units also can be evaluated with respect to the extent of treatment necessary during the planning and designing stage of the efnuent treatment plants. The final effluent characteristics can be predicted and made to comply with the requirements prescribed by the regulatory authorities.

APPENDIX A

( Clause 0.5 )

REFERENCES

ALAGAKSAMY ( S R ), BHALEKILO ( B B ) and JZAJAGGPALAN ( S ) Treatment of wastes from fertilizer plants. Irdfan J. Environ. 15, 1 ; 1973 ; 52.

AUSTIN ( R J ) and VANSE ( E H ). Chemical Coagulation of refinery waste water. Proc. of 6th Industrial Waste Conference. Purdue Univ. I-eb. 1951; 272.

BAUMANN ( R E ). On removal of ammonia by air stripping -- EPA Design seminar, Kansas city, USA 197 1.

BENIUB~ ( F W ) and SPALI. ( B C ). A review of effluent problems in fertilizer manufacture Paper presented at the Seminar of the Fertilzer Society of London, April 1976.

*Tolerance limits for industrial effluents discharged into inland surface waters (/;r,sr revision ):

Part J-1974 General limits (first revision ) Part VIJJ-1976 Phosphatic fertilizer industry (first revision ) J>art 1X-1977 Nitrogenous fertilizer industry (first revision j

IS : YH41 - 1981

5.

6.

s < .

0.

IO.

1 I.

12.

13.

14.

15.

16.

17

18.

19.

20.

13IIArrACtl,~RYA ( G 5: ), Roy ( G S ). J~vI.RJ~.F ( c‘ D ) and Di-ri I ( lj K ), lii~i~~o- val of Huorides and phosphorous from phosphatlc lertiltzer factory \ba\te,. I“:i’Ci presented in the seminar “IJtlli/ation and Disposal of Industrial M a\tcs” ,>rg.li!i,c<j by I. I. C‘h. E ( Calcutta ) at Jadavp~u Univerbtt)‘, DCC lY7;

1jtIATTACHAKYA ( <i s ), &Y ( G s ) Xld DUI I’A ( 13 K ). InbeStigatltIfl II,CO it::

use of algae for removing ammonium nitrogen from nitrogenous ind~‘~rr~,ii II,I,I~, Part 1 Tec~/rm/ 3 ; 3 ; lY66 ; 135. Part II ZT/IW/ 5 ; I ; lYh8 ; 31.

Brta~rrA(‘tlARyA ( G S ), ROY ( Ci S ) and I)UrTA ( H K ). Treatment and cII\P~~\.II of efBucnts of modern urea fertilizer factories. Tdr!7ol 6 ; 1 ; 1969 . 62 I’dper

presented in scmlnar on “lndu~trial w.lstc” at I. I 1 ., Kanpur l’j69.

~AT~~~AC~~AHYA ( <; s ), SAKlcAK ( c 1.) ) alld &I IA ( 1% K ). ~‘hOSphdtC POhiiC~!l

and its effects on water treatment. hoc. S\im. of water pollution cnrltr01 in 1)~~ IOhS C’IHPEKI ~- Nagpur ( 1966 ).

I<IiAY’TACtIAHYA ( s K ), BtIATrACHAIIYA ( c; s ) :tnd I)t,TrA ( u K )_ Kenl(~\al <,! nitrogen from nitrogcnc,us effluent. ‘Tr~,lr~~jl IO ; 3: 1 : 1973 ; ??_I.

bINbllAM ( E C ). Solutions for minjmum pollution in nitrogen Industry. Lhl 110 Expert Group meeting on minimi7ir,g pollution from fertilii-cr plants. llclsinhi Aug. 1974.

HINC~IIAM ( 1-t C ) and CIIUIJHA ( Ii C ). :\ unique closed cycle water s)stcm Iljr lil~ ammonium nitrate producer using Chem-scps continuous counter current 1ut1

exchange. Proc. of 32nd Internattonll Water Conference of the Engs SOC of \\ ei: Penn. Pillsburg, USA I\lov 1971.

BHIN(;UA~U~+ ( G ). On nitriticatioii and dcnitrification 111 SeWcige treatment. J. lJ’t~t~rrft.r Poll Ahr. 17 , I964 ; 18.

CHATT~RJLI: ( D 1) ), SRIVASTAVA ( A C ) and DUTTA (, B K ). Hydrogen cyamdc removal from weak aqueous potassium cyanide solution. Technoi. 13 ; 4 ; I’)76 : 273.

Coon ( N E ) and Coo~v.~~ ( K M ). Some aspects of pollution control at a large fertilizer complex. Ammonia Plant safety symposium of the 3rd Joint meeting AlCLE-IHIQ, Denver, Colorado, USA Aug-Sept 1970.

CULIJ ( G L ) and CUI.P ( R L ). On stripping of ammonia from efluents. Advanced waste water treatment. Van Nostrand, Reinhold. New York 1971,

CULP ( R L ). On air stripping of ammonia from effluents and water reclamation. .I. Amer. WL)IPT wkr Assn. 60 ; 1968 : 84~

DAS ( A C ), Krt~iu ( J A ) and DLJTTA ( J.3 K ), Kemoval of nitrogen from the fertilizer factory effluents hy biochemical nitrification and denitrification. Techrrol 3 ; 4 ; 1966 ; 41. Spl issue of seminar on wastes and etiuents in chemical mdusrrles.

DE LOKA ( F Y ) and MASIA ( A ). Influence of effluent standards on the econo- mics of alternate waste water treatment designs ; UNIDO Expert Group meeting on minimizing pollution from fertilizer plants. Helsinki Aug 1974.

DJJKSAKA ( F ). Measures to minimire aqueous waste pollution from fertihzer plants situated in an integrated chemical complex. UNIDO Expert Group meeting on minimizing pollution from fertili,rer plants, Helsinki Aug 1974.

39

IS : 9841 - 1981

1jrr.1 r,z ( 13 K ). Removal of ammonia from fertilizer plant effluents. Paper prcsen- ted in ,411 India Symposium or: Efllucnt Treatment organized hv ICTI) Bomha~. Ma> IOSO.

1~:. I’. ;\. USA Fcdcral Kegistcr .?‘I ( 6X ) April S ( 1974 ) : 30 ( 9 ) Jan 1-l I 1975 i : 30 ( 121 ) Jun 72 ( I975 ) ; JI ( I I ) Jan I6 ( 1970 ) ; .II C ‘9s ) $1~1~ IO ( 1970 1. 4t , 13X ) July Ih ( 1976 ).

tIowI. I<olcr I< I ( It L ). On prc,cesac\ for removal of cj,2nldc frtjnr naste Mater. I’roc. ()I‘ the 18th industrial waste conference. Purdue UnlverGty, 4pril-MaylOh~.

II\.<; ( 4 ). l%>llution f-rtm i’ertllirer plants in Bangladesh. UNIDO 1:xpcrt Group meeting on minimrling pollution from fertilizer plants Helsinki, Aug. 1074.

JOIINSON ( W K ) and S~III~~~IYIK ( G J ). Nitrogen removal by nitrificatlon and denitrification. .1. IV~‘o/f’,. I+,//. (;,,rff. /;t,c/. 41 ; I971 ; 1x45.

~.IIJTAK BILA ( <i ). Removal of’cyanidc and chromium. Environmental Engineers Handbook vol 1 M’ater pollution. Chilton Book Co. US.4 p 1365 1782.

Pollution control In fertilizer industry Part I. t~-\I Report Tech J. 1079 t-crtlllzer ~ssrrc. of India, New Dclhl.

PROSAI) ( Ii R ) and L)u.rr~ ( !3 K ). A study of etlluents 01 Sindri Fertillret Factory. ~~hnol 3 : 4 : 1966 ; 65 Spl. issue. Seminar on wastes and dIlucnts 1n chemical industry.

Roy ( G S ), I~I-I,\~I~.I~ACC~AI~YA ( G S ) and Dutta ( B K ), rreatment and disposal of effluents from fertilizer industries. Techr~ol 7; 3 ; 1970 ; 193. Paper presented in seminar on ‘Water pollution and industrial waste treatment’ in Bangalore, Dee 190q.

SRIVAS~AVA ( A c ) and L)UTTA ( I) K ). Ammonia recovery from coke oven industries by an ion exchange process, T~C/VIO/ 7 ; 4 ; 1070 ; 66 spl. Issue on seminar on cual and coal chemicals. Nov. 1968.

The Water ( Prevention Xr Control of Pollution ) Act. 1974 Govt. of India.

b’HALI.EY ( L ). Modern technology for minimizing pollution from fertilizer plants. UNIDO Expert Ciroup meeting on minimiz.ing pollution from Fertilizer plants. Helsinki. Aug 1074.

40

IS : 9841 - 1981

( Continued from page 2 )

Members Representing SHRI R. M. SHAH Tata Chemicals Ltd, Bombay

SHRI R. K. GANDHI ( Alternate ) SHRI P R. SHETH Excel Industries Ltd. Bombay

SHRI S. P. IYER ( Ahernafe ) DR V. SREENIVASA MURTHY Central Food Technological Research Institute

( CSIR ), Mysore SHRI M. S. SUBBA RAO ( Alternate )

SHRI S. B. TAG~R~ Department of Environmental Hygiene ( Govt of Tamil Nadu ). Madras

DR ( SMT ) S. M. VACHHA

DR HARI BHAGWAN.

Director of Heaith Services, Government of Maharashtra, Bombay

Director General, ISI ( Ex-oficio Member ) Director ( Chem )

Secretary

_.

SHRI N. K. SHARMA Deputy Director ( Chem ), IS1

Waste Treatment Methods Subcommittee, CDC 26 : 1

Convener SHR~ A. RAMAN National Environmental Engineering Research

Institute ( CSIR ), Nagpur

Members SHRI B. V. S. GURUNATH~O ( Alternate to

Shri A. Raman) DR R. N. CHAKRABARTY Universal Enviroscience Pvt Ltd. New Delhi CHIEF WATER ANALYST, KING Director of Public Health, Government of Tamil

INSTITUTE, MADRAS Nadu, Madras SHRI L. M. CHOUDHRY Haryana State Board for the Prevention & Control

of Water Pollution, Chandigarh SHRI M. L. PRABHAKAR ( Alternate )

DR D. CHOIJDHURY Indian Chemical Manufacturers’ Association, Calcutta

SH~I V. K. DIKSHIT ( Alternate ) SIIIU B. D. DUHMUKH Maharashtra Prevention of Water Pollution Board,

Bombay DJRECTOR ( C. S. & M. R. S ) Central Water Commission, New Delhi

SHRI N. C. RAWAL ( Alternate ) SHRI B. K. DUTTA Fertilizer ( Planning & Development ) India Ltd,

Sindri SHRI G. S.. RAY ( Alternate )

SHRI R. C. DWIVEDI Uttar Pradesh Water Pollution Prevention & Control Board, Lucknow

SH~U S. P. SAXENA ( Alternate ) DR A. K. GUPTA Hindustan Fertilizer Corporation Ltd, Durgapur

SHRI T. P. CHA~~ERJ~~~ ( Akernafe )

( Continued on page 42 )

41

IS : 9841 - 1981

Members Representing

SHKI S. GUPTA Central Board for the Prevention and Control of

DK H. S. MATHAK~~ ( Alfernate ) SHRI R. V. KADAM

SHRI N. V. VASHI ( Alfernare ) SHRI K. R. KRISHNASWAMI SHRI V. N. LAMRU

SHKI V. V. JOSHI ( Allenrate ) SHRI A. K. MAJUMDAR

SHRI U. C. MANKAU (Alternate ) SHRI S. V. MANI

SHRI S. R. LUTHRA ( Alfernate ) SHRI V. S. MORE

Water Pollution, New Delhi

Paramount Pollution Control Pvt Ltd, Vadodara

Madras Fertilizers Ltd, Madras Ion Exchange, ( India ) Ltd, Bombay

Geo Miller & Co Pvt Ltd, Calcutta

Greaves Cotton & Co Ltd, Bombay

Indian Oil Corporation Ltd ( Refineries & Pipelines Division ), New Delhi

SHKI PAKAMJW SINGH ( Alternate SHIU D. V. S. MURTHY

DR G. K. KHARE ( Akmate ) SHRI R. NATARAJAN ’

SHRI AMI.I. S. DESAI ( Alternute ) DR V. PACHAIYAPPAN

DK R. N. TRIVEDI ( Alternate ) Jh R. PITCHAI SIIRI H. S. PrJRI

SHRI QIMA.I. RAI ( Alternale ) SHRI JOHN RAJU

SHRI A. P. SINHA ( Alternate ) SHRI M. K. ROY SHRI J. M. TULI

SHRI K. RUDRAPPA ( AJternate ) SHRI T. K. VEDARAMAN

DR S. R. SHUKLA ( AJternate )

of Water Pollution, Patiala

Steel Authority of India Ltd, New Delhi

Chief Inspectorate of Factories, Ranchi Engineers India Ltd, New Delhi

Ministry of Works & Housing

Panel for Fertilizer Industry Wastes. CDC 26 : 1 : 12

Convener

SIIRI B. K. DUTTA

Members

SHRI G. S, RAY ( Alternate to Shri B. K. Dutta )

DR R. N. CHAK~UBARTY DR S. K. GUPTA ( Alternafe )

SHRI P. P. CHANDHNA SHRI V. CHARANDAS

SHRI M. D. PATEL ( Affernate ) SHRI L. M. CHOUDHRY

M. P. State Prevention & Control of Water Pollu- tion Board, Bhopal

Hindustan Dorr-Oliver Ltd, Bombay

The Fertilizer Association of India, New Delhi

College of Engineering, Madras Punjab State Board for the Prevention & Control

The Fertilizer ( Planning & Development ) India Ltd. Sindri

Universal Enviroscience Pvt Ltd, New Delhi

National Fertilizers Ltd, New Delhi Gujarat State Fertilizers Co Ltd, Vadodara

Haryana State Board for the Prevention & Control of Water Pollution, Chandigarh

SHRI M. L. PRABHAKAR ( Alternate ) ( Conrinued on page 43 )

42

( Continued from page 42 )

Members Representing

SHRI K. P. DOHARE Directorate General of New Delhi

SHRI K. V. SAMPPTH ( Ahvrate )

Technical Development,

SHRI A. N. DUTTA CHOUDHURY Board for Prevention & Control of Water Pollu-

IS:9841- 1981

tion, Assam, Gauhati SHRI B. K. CHOUDHURY ( Alternate )

DR A. K. GUPTA Hindustan Fertilizer Corporation Ltd. Durgapur SHRI T. P. CHATTERJEIZ ( Alternate )

SHRI V. V. JOSHI Ion Exchange ( India ) Ltd, Bombay SHRI S. K. BHA~ACWARYY~ ( Alternate )

SHRI S. MALLICK Indian Exolosives Ltd. Kanuur _ 33~1 T. N. MEI~ROTRA ( Alternate )

PROF R. S. MEF~TA Gujarat Water Pollution Control Board, Gandhi- nagar

SHRI R. NATARAJAN Hindustan Dorr-Oliver Lid, Bombay SHARI A. G. NCNE Shriram Chemical Industries, New Delhi DR R. K. NIYO~I Hindustan Lever Ltd, Bombay

SHRI S. K. SU~BAR~~..I~X ( Alternate ) DR V. PACHAIYAPPAN The Fertilizer Association of India, New Delhi

DK R. N. TKIVEDI ( Alternare ) SIIRI D. PANIGRAHI The Fertilizers Rr Chemicals, Travancore Ltd.

Udyogamandal SHKI N. J. JOSLYH ( Alternate I ) SH~I K K. Jose: ( Alternafe II )

SHRI ‘r. C. PITCHAPPAN Madras Fertilizers Ltd, Madras SHRI K. R. KRISHNASWAMI ( Alternate )

SHRI H. S. PUKI Punjab State Board for the Prevention & Control of Water Pollution, Patiala

SHHI QIMAT RAI ( Alrernaie ) SHRI K. RUDKAI’PA E:ngineers India Ltd. New Delhi

SHIU A. D. JALONKAR ( Alrernotc ) DR K. L. SAXENA National Environmental Engineering Research

Institute ( CSIR ), Nagpur DR T. CHAKRABORTY ( Ahnate )

33

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